<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
</head>
<body>
    
</body>
<script>

    //1.定义函数
    // function add(a,b){
    //     return a + b;
    // }

    //2.定义函数
    var add = function(a,b){
        return a + b;
    }

    //函数调用
    var result = add(10,20);
    alert(result);
</script>
</html>